A Variational Multiscale Framework for Analysis of Wind Turbines in Complex Terrain

Date
2019-12
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Abstract
Current industry tools for analyzing the flow field around wind turbines in complex terrain do not include all the non-linear physical effects present in reality. A residual based variational multi-scale (VMS) modeling framework is applied to simulate atmospheric flow over complex environmental terrain. This is coupled with the actuator line method (ALM) which represents the effects of the turbine blades on the flow as a distributed body force. To validate the VMS framework for complex terrain, we use three test cases. For a Gaussian hill (normally distributed surface), stream-wise velocity aligns well with published data. The second validation case is the Bolund hill, for which experimental field study data exists. Simulation results compare well in most regions. For both test cases, the VMS framework is applied to linear finite element and quadratic NURBS (Non-uniform rational b-splines). NURBS elements have been shown to give better results than linear finite elements and that is also found here. Finally we simulate flow over the double ridges at Perdigao, Portugal. To validate the ALM-VMS implementation, the National Renewable Energy Lab (NREL) 5MW reference turbine is simulated under uniform inflow conditions to investigate the effect of model parameters such as the width of the body force projection and the mesh resolution. Additionally, the wind turbine from the Norwegian University of Science and Technology and the NREL Phase VI wind turbines are simulated and compared with results from the corresponding wind tunnel experiments. Velocity deficit and turbulence kinetic energy in the wake region between three and five down-stream diameters show good agreement with experimental data. Finally, we simulate an NREL 5MW turbine in the complex terrain at Perdigao, highlighting the ability of the developed framework for wind turbine applications in complex terrain.
Description
Keywords
Computational Fluid Dynamics, Fluid dynamics, Wind energy, Complex terrain, Finite element method, Variational multiscale
Citation
Ravensbergen, M. (2019). A Variational Multiscale Framework for Analysis of Wind Turbines in Complex Terrain (Master's thesis, University of Calgary, Calgary, Canada). Retrieved from https://prism.ucalgary.ca.